Abstract

The present paper is an attempt to illustrate the point that the basic issues in Aristotle’s practical philosophy in analyzing Heidegger’s existentialism are conceived of as the matter of ontology. Comportment of men in reference to beings mentioned in Book Six of Aristotle’s Nicomachean Ethics turns into comportment of constitution in the new approach to Heidegger’s Being and Time. What is of great significance for Heidegger is reviving the hidden ontological power present in the three fundamental modes of activity in Aristotle’s theory in which praxis is preferred to two other modes of activity drawn from being, i.e. theorie and poíésis. Heidegger diagnosed some proper definitions and descriptions regarding human life in Aristotle’s transcendental idealism which are not known in modern philosophy as in Husserl’s philosophy. If we reconsider existentialism under the shadow of Aristotle’s phenomenology and specially Nicomachean Ethics, we may find ways to better interpret Heidegger’s philosophy.